Scan2CAD raster to vector conversion software

REVIEW:

Graphtec CSX300 large format scanner

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Accuracy

We scanned an A0 (E-size) drawing. We measured the lengths of the lines on the drawing and compared them to the lengths of the scanned lines. We found the scanner's accuracy to be well within its published tolerance of +/- 0.1% with a less than one mm (0.04") error across the entire width and length of the drawing.

The CSX300 also includes a facility for temporarily adjusting accuracy along the scan, which may be affected by different media types.

Resolution

We scanned a standard T-10 resolution chart (see our large format scanner resolution article).

Five cycles per mm is the smallest test element on the T-10 chart where we are just about able to resolve individual lines by eye. Lines closer together than this cannot be resolved by the human eye and so are unlikely to be found on a CAD drawing.

Below is the 5 cycle per mm test element scanned by the CSX300 along with the same test element scanned by the Graphtec SK200 and Graphtec CS600, displayed at 1 pixel on the scan = 1 pixel on the screen size.

CSX300 SK200 CS600

The lines are easily resolvable, although the scan made by the CS600 (now replaced by the CS610) looks slightly sharper than the CSX300 and SK200 scans. (All three scanners are CIS technology scanners with 600 dpi optical resolution.)

What is very interesting is when you compare scans made using different scanning modes. The CSX300 has three scanning modes: High Quality, Normal and High Speed. Here are scans made with the CSX300 in each mode:

High Quality Normal High Speed

You can see that in High Quality mode, both the horizontal and the vertical lines are resolvable. In Normal mode, the vertical lines have blurred into each other. In High Speed mode, both the horizontal and the vertical lines have blurred into each other.

How does this affect a real drawing?



Lines scanned using High Quality mode.


The same lines scanned using High Speed mode.


On the left is part of a real mechanical drawing scanned at 400 dpi using High Quality mode, and the same drawing section scanned using High Speed mode.

As you can see, High Quality mode separates the lines perfectly, but using High Speed mode the lines have joined.

This would seriously degrade the quality of the results you would get if you were to convert the scan to vectors using raster to vector conversion software such as Scan2CAD.

We would conclude that the CSX300's resolution is more than adequate for CAD, but we would strongly suggest that CAD users scan using the High Quality mode.

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